Low Carb Diets and Physical Performance - Recent Studies Show Performance Decrements in Average Joes + Athletes

If the above are the ingredients you are using when you prepare your meals, your diet is almost certainly not a low carbohy-drate high fat, but a low carbohydrate high protein diet. Please mind the difference and don't brag in the comments about how great you feel on your "keto diet"!

If you are an avid follower of the SuppVersity News on Facebook (revisit the post), you will remember Louise M. Burke's late 2016 paper which showed that a low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers" (Burke 2016).

Accordingly, Jørn Wulff Helge from the Center of Healthy Aging in Copenhagen, Denmark, wrote in his recent perspective article in The Journal of Physiology that "in elite athletes training and performing at intensities similar to elite sports competition, keto-adaptation is not the optimal dietary choice" (Helge 2017).

You know, high-protein diets are safer than people say, but there are things to remember...

Practical Protein Oxidation 101

5x More Than the FDA Allows!

More Protein ≠ More Satiety

Protein Oxidation = Health Threat

Protein Timing DOES Matter!

Keto for Superior Weight Loss?

Complementary results for less trained individuals has now been published by Urbain et al. (2017) in the peer-reviewed journal Nutrition & Metabolism - a paper in which the authors report an, albeit "mildly negative", impact of a 6-week non-energy-restricted ketogenic diet on physical performance (endurance capacity, peak power, and faster exhaustion)" (Urban 2017).

Can these observations be surprising? No, they can't. After all, even the most dedicated keto-proponents, like Stephen Phinney acknowledge that "[i]mpaired physical performance is a common but not obligate result of a low carbohydrate diet" (Phinney 2004) - whether and to which extent the effects that were observed in the previously cited studies could have been fixed, as Phinney suggests using his notorious references to "traditional Inuit culture" by "optimized sodium and potassium nutriture, and constraint of protein to 15–25 % of daily energy expenditure" will be discussed in the bottom line of this article. First, however, let's take a look at the methodology and results sections of the Burke and Urban papers.

Low carbohydrate + high-fat diet impairs walking performance and adaptation

Let's address one of the often heard criticisms of this study right away: the subjects didn't eat enough... true! During the three weeks of intensified training, the dietary intake was limited to 40kcal/kg and thus roughly 2400kcal/day, not increased to compensate adequately for the increased energy requirements due to high volume race walking, resistance training and cross-training (running, cycling or swimming | for details see Table 1).

Table 1: Overview of weekly training-diet intervention involving high carbohydrate (CHO) availability (HCHO), periodized CHO availability (PCHO) or low CHO high fat (LCHF) diets in elite race walkers (n = 29 | Burke 2016).

Accordingly, the subjects were in a slight but significant caloric deficit of ~400-450kcal of which Burke et al. expected that it would trigger a 1-1.5kg fat loss over the course of the 21-day study period.

Figure 1: Graphical overview of the study design (I added extra info on the diet | Burke 2016).

You can see all the details about the training and dieting regimens that included both, a high CHO, a cyclical / periodized CHO and the classic Volek / Phinney style ketogenic (Volek & Phinney 2012) diet in Figure 1 (please understand that the LAB, FIELD and LAB test were repeated before and after the training weeks which may be easily overlooked at the bottom of the illustration | see Table 1, too).

Figure 2: Pie charts of the relative contribution of fat, protein, and carbohydrates to the total nutrient intake of 40kcal/kg body weight (~2400kcal/d) the subjects received over the course of the 3-week study period (calc. based on Burke 2016).

To spare you reading all the small print in Figure 1, I also plotted the macronutrient ratios as pie charts in Figure 2. In that, I used the average energy intake as a basis to calculate the 8% CHO intake in the "keto" (LCHF) group as a maximal contribution of carbohydrates to their diet based on the upper intake limit of 50g of carbohydrates per day (the actual contribution of carbohydrates to the total energy intake may thus have been <8% of the total energy on many days). With so little carbs in the LCHF group, it is not surprising that

• the ketogenic low-carbohydrate, high fat (LCHF) diet markedly increases rates of whole-body fat oxidation during exercise in race walkers over a range of exercise intensities.

In view of this increase in peak aerobic capacity, it will be either surprising or re-affirming, depending on whether you're a keto-advocate or -skeptic, that the low carbohydrate and high-fat diet... 

• significantly reduced the subjects' running economy (increased oxygen demand for a given speed) at velocities, and thus 
• translated to real-life race performance decrements in the elite race walkers.

Worth mentioning and actually something to consider for those of you who want the best of both worlds is that the periodized high carbohydrate intervention did not trigger a similar performance impairment in the highly trained subjects of Burke's latest low-carb study.

Ketogenic diet without energy restriction impairs exercise performance in healthy adults

The latest contribution to the accumulating evidence that a high-fat, low carbohydrate diet may, irrespective of any weight loss or health benefits it may have or not have, be not the ideal choice for athletes and wanna-be athletes comes from the University of Freiburg in Germany, where Urbain et al. found the previously cited "mildly negative impact from this 6-week non-energy-restricted KD on physical performance (endurance capacity, peak power and faster exhaustion)" (Urbain 2017) in a group of n=42 normal-weight, healthy adults who got less than 10% (< 20–40 g/day) of their daily energy intake from carbohydrates, 75% from fat, and 15–20% from protein over the course of the 6-week study.

The subjects were free to choose the foods they were eating, the overall caloric diet was not restricted, and their adherence to the carbohydrate limit was tested by daily measurements of urinary ketones and keeping 7-day food records.

Figure 3: Changes (% relative pre vs. post change on top of the bars) in body composition, active thyroid hormone and resting energy expenditure from pre vs. post 6-week high-fat, low carbohydrate dieting in healthy subjects (Urbain 2017).

As you can see in Figure 3, the subjects lost a significant amount of lean and fat mass over the course of the intervention. That's surprising, since the subjects'...

• resting energy expenditure (REE) dropped by 6%, from 1523 kcal/day to 1430 kcal/day (free active thyroid hormone concentrations, i.e. fT3, which declined by 13%) while 
• mean daily caloric intake during the study did not change from the previous habitual diet (PRE 2321 ± 551 kcal/day, POST 2224 ± 584 kcal/day; P = 0.186). 

Whether or to which extent the weight loss was a side effect of ketosis is difficult to tell. What is certain, however, is that the subjects' adherence was, with 7.7% of the energy coming from carbohydrate and confirmed ketosis in 97% of the tests, excellent.

"But eating a ketogenic diet will make you lose weight and improve your health..." While that is something you can read abou everywhere on the internet. The contemporary evidence is everything but clear. Yes, in the obese and diabetic, there's evidence that a ketogenic diet will produce both weight loss and improvements in metabolic health. Whether or not it does this more successfully than other sane diets (i.e. not the one recommended by the American Diabetes Association), such as a Mediterranian or a high(er) protein moderate fat and carbohydrate diet, is yet questionable - even in obese and diabetic subjects.

Changes in markers of metabolic health in the Urbain study. As in comparable studies, lipids increased, glucose and the related trigs decreased - all within normal levels.

The studies at hand, which dealt with healthy and normal-weight subjects, don't support the often heard of clear superiority of ketogenic dieting, either. And that's for both: Body composition, where the Burke study didn't find inter-group differences in weight loss (and did not assess body composition) and the Urbain observed a weight loss that could be due to a reduced energy intake in the early weeks, when many subjects reported side effects, but did not lead to an improvement in body composition. As well as the subjects' metabolic, which wasn't even tested in Burke et al. and about which we cannot make a definitive statement based on the ambiguous results of the Urbain study, where the blood lipids worsened (LDL and total cholesterol went up, HDL stayed the same) the glucose and insulin levels decreased - both within healthy limits, though).

By no way excellent, however, were the results of the repeated exercise tests. While the subject obviously ate enough and also kept their habitual physical activity levels, the subjects' ...

• VO2peak, the study's primary endpoint, decreased significantly from 2.55 ± 0.68 l/min to 2.49 ± 0.69 l/min (P = 0.023) by 2.4%, 
• peak power Pmax decreased significantly from 241 ± 57 W to 231 ± 57 W by 4.1%, 
• rating of perceived exertion increased slightly from 17 (13–19) to 18 (14–19) (P = 0.052)

The participants' ventilatory threshold, their maximal heart rate and even the relative VO2peak (=VO2peak divided by body weight) were not affected by the KD intervention. Especially the latter observation is interesting. After all, it raises the question whether the statistically "large" effect size on the VO2 peak (d = 0.088) is practically relevant (and highlights the need to understand the underyling cause of the weight loss).

Figure 4: Relative pre- vs. post changes (%) in Spiroergometry, EKG and Borg scale (Urbain 2017).

In their own conclusion, the scientists point out that their results only partly conflict with previous studies. While both, Phinney et al. (1983) and Klement et al. (2013) found that the aerobic capacity was not compromised by a ketogenic diet and Zajac et al. (2014) even report a significant relative VO2peak improvement (probably a consequence of the sign. weight loss in the study), the more significant reduction in peak power Urbain et al. observed is in fact consistent with results others have reported (Zajac 2014, Klement 2013). Even in the previously cited studies by Zajac et al. (2014) and Klement et al. the peak performance dropped by 3.3% and 1.5% respectively.

Low(er) Carb Crossfitters May be Missing Out | 11.1% vs. 4% Rep Increase With 6-8g/kg CHO in 12-Min Rohoi Benchmark  - Expect the same for other sports that involve long(er) lasting anaerobic activities | more

Bottom line: If we take the results of both studies, as well as related previous studies into account, it becomes obvious that both training status and type of exercise matter when we talk about the potential negative effects on a subjects' exercise performance.

For endurance exercise in non-athletes, the previously discussed conflicting evidence suggests that the last word has not been spoken yet (the previously mentioned "opti-mized sodium and potassium nutriture" (Volek 2012) could make a difference here, as well). For endurance athletes, on the other hand, the increase in fatty oxidation does not appear to be able to compensate the lack of readily oxidizable glucose. Thus, "in elite athletes training and per-forming at intensities similar to elite sports competition, keto-adaptation is not the optimal choice" (Helge 2017).

The study's main research focuses doesn't allow for conclusive statements about athletes and gymrats whose sports are mostly anaerobic, but in view of the correspondingly higher glycolytic demands of these sports, it's hard to imagine that (again all health and body composition goals aside) a sprinter or cross-fitter would be better off on a low carbohydrate, high fat diet. Whether the often marginal performance decrements outweigh the individual benefits on your well-being and/or body composition is something each of you will have to decide on his/her own | Comment!

References:

• Burke, Louise M., et al. "Low Carbohydrate, High Fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers." The Journal of Physiology (2016).
• Helge, Jørn Wulff. "A high carbohydrate diet remains the evidence-based choice for elite athletes to optimize performance." The Journal of Physiology (2017).
• Klement, Rainer Johannes, et al. "A pilot case study on the impact of a self-prescribed ketogenic diet on biochemical parameters and running performance in healthy and physically active individuals." Nutr Med 1.1 (2013): 1-27.
• Phinney, Stephen D., et al. "The human metabolic response to chronic ketosis without caloric restriction: preservation of submaximal exercise capability with reduced carbohydrate oxidation." Metabolism 32.8 (1983): 769-776.
• Phinney, Stephen D. "Ketogenic diets and physical performance." Nutrition & Metabolism 1.1 (2004): 2.
• Volek, Jeff, and Stephen D. Phinney. The Art and Science of Low Carbohydrate Performance: A Revolutionary Program to Extend your Physical and Mental Performance Envelope. Beyond Obesity, 2012.
• Zajac, Adam, et al. "The effects of a ketogenic diet on exercise metabolism and physical performance in off-road cyclists." Nutrients 6.7 (2014): 2493-2508.

450-700kcal/day Diet Cuts 7% Body Fat in 3 Weeks - Only if You go Keto, Though, it Will also Increase Lean Mass by 4%

Not basing both the ketogenic and regular very low calorie diet on whole foods, only was only one of at least 3 problems with the study at hand that can thus not be considered the ultimate litmus test to compare VLCD with en vogue VLCKD diets.

Ketogenic diets are characterized by constantly low insulin levels. That's not exactly what has been considered muscle protective in the old age of bodybuilding, where insulin's protein-anabolic and anti-catabolic effects were still hailed as a benefit you wouldn't want to miss (Fulks. 1975; Woolfson. 1979), but according to a recent study from Rome, a ketogenic diet may be the go-to diet for everyone trying to shed as much as weight as possible in as little time as possible by cutting your total daily energy intake down to a hilarious <700 kcal/day (Metta. 2016).

Now, cutting calories back that much may sound (and be) idiotic for someone who has been lean all his / her life and is just trying to make his abs more visible. For someone whose overweight is threatening his life, it may be a life saver...

You can learn more about improving your body composition at the SuppVersity

Long-Term Dieting Makes Gymnasts Fat!

Minimal Carb Reduction, Max. Results?

HIT Circuit + Plyos for Glucose Management

How Much Carbs Before Fat is Unhealthy?

5 Tips to Improve & Maintain Insulin Sensitivity

Weight Must be Lost Slowly? Busted!?

It can be a life-saver that backfires if you end up losing the already low amount of metabolic currency (=skeletal muscle) that has remained unused under a thick layer of body fat for years, though. To avoid that from happening Metta et al. (2016) randomized twenty-five healthy subjects (18 and 65 years, with a BMI ≥ 25 kg/m², percentage of body fat (PBF) ≥ 25 for male, and ≥ 30 for female) randomly (R) divided into two groups (X and Y). The group X received the VLCKD, and the group Y received the VLCD - both for 3 weeks over which 3 subjects dropped out:

• The very-low-carbohydrate ketogenic diet (VLCKD) aimed at an energy intake of 450-500 kcal per day for female and 650-700 kcal per day for male, with 35-40% of calories from fat, < 10% of calories from saturated fat, 5% of calories from carbohydrates (< 6 g), and 55-60% of calories from protein, corresponding to 1.2 g (female) or 1.5 g (male) / kg of body weight, and an intake of 25 mg of fiber per day. The half of the amount of daily protein was reached using aminoacid supplement, called Amin 21K (Italfarmacia, Rome, Italy | product website). The powder of aminoacid was dissolved in water and drunk at the breakfast and lunch or dinner.
• The very low restricted-calorie diet (VLCD) aimed at an energy intake of 450-500 kcal per day for female and 650-700 kcal per day for male, with 35-40% of calories from fat, < 10% of calories from saturated fat, 15-20% of calories from carbohydrates (< 20 g (female) or < 30 g (male), and 45-50% of calories from protein, corresponding to 0.9 g (female) or 1.1 g (male) / kg of body weight, and an intake of 25 mg of fiber per day.

In both groups, a capsule of multivitamin, proper integration of mineral salts and an alkalizing product were prescribed. The correct administration of diet was evaluated by urinary keto-stick. The study was conducted in double-blind fashion and the subjects were asked not to change their lifestyle habits.

Figure 1: Changes in body composition over the 3-week study (N=18 subjects remained | Metta. 2016).

In view of the identical energy and protein intakes (45-50% of calories), the DXA-based body composition data in Figure 1 is unquestionably impressive, as it seems to support the notion that cutting out carbs from a nutritionally clearly deficient diet was enough to turn a hunger diet into a muscle-preserving fat burning wonder diet, but...

1. on a per/kg basis the protein intakes were everything but identical - with 0.9g/kg in the female and 1.1g/kg in the male study participants of the normal carbohydrate (VLCD) arm of the study, the ketogenic (VLCKD) diet provided 33% and 36% more protein for the female and male study participants, respectively;
2. the subjects in the VLCKD group got sign. amounts of protein from a whey + extra-EAA supplements - the supplement that is based on whey protein plus potassium citrate, L-isoleucine, ornithine alpha-ketoglutarate, L-tryptophan, taurine and L-citruline alone could have made all the difference;
3. the baseline characteristics of the randomly formed groups differed - with the VLCD group being sign. fatter (80% were obese vs. only 16.67% in the VLCKD), which is obviously a problem you cannot ignore when interpreting the results;

Against that background, you must not get all to psyched about what you see in Figure 1 - at least with respect  to the significance of the results with respect to confirming the superiority of ketogenic very low calorie diets over regular very low calorie diets... not the least, because we don't really know what the mechanism behind the benfit can be - is it: (a) reduced adrenergic influences, (b) increased production of ketone bodies that directly effect extra-hepatic tissues including brain and muscle, (c) amelioration of the blood sugar induced reduction in GH prodution or (d) high(er) / greater quality protein intakes - all that could interac with insulin and individual (epi-)genetic dispositions of the subjects.

"Keto Diet Research: Body Weight & Fat Gain, but not Muscle Protein Synthesis After Exercise is Impaired in Rodents in Ketosis" | read it

So what does the study confirm, then? It's not nothing, don't worry. After all, the study confirms that going low carb when you starve yourself and helping your muscles survive with an slightly 'enhanced' whey protein product.

Since it is not clear to which extent the previously discussed extra-advantages of the ketogenic diet group affected the study outcome, however, more and better controlled studies that are specifically designed to assess the combined effects of genotypes and dietary intervention, as well, will be necessary to make definitive statements about whether the "keto-advantage" is in fact as significant as the data in Figure 1 appears to suggest | Comment!

References:

• Fulks, Richard M., Jeanne B. Li, and Alfred L. Goldberg. "Effects of insulin, glucose, and amino acids on protein turnover in rat diaphragm." Journal of Biological Chemistry 250.1 (1975): 290-298.
• Merra, G., et al. "Very-low-calorie ketogenic diet with aminoacid supplement versus very low restricted-calorie diet for preserving muscle mass during weight loss: a pilot double-blind study." European Review for Medical and Pharmacological Sciences 20 (2016): 2613-2621.
• Woolfson, Anthony MJ, Richard V. Heatley, and Simon P. Allison. "Insulin to inhibit protein catabolism after injury." New England Journal of Medicine 300.1 (1979): 14-17.

Ketogenic Diet Research: Total Body Weight and Fat Gain, but not Muscle Protein Synthesis After Exercise is Impaired in Rodents on Ketogenic Diet | ISSN Research Review '15 #4

I don't know what exactly was in the ketogenic rodent chow that was used in the study at hand, but I doubt it were transfat laden sausages ;-)

Welcome to the fourth issue of the SuppVersity ISSN '15 Research Review... as you will notice I am trying to make the introductions shorter and shorter with each installment of this series. So, let's not waste time and dig right into the latest research on ketogenic diets.

Yes, you heard me right. There is new research on ketogenic diets that does not focus on weight loss, the obese and/or cancer. Rather than that, the studies discussed in this installment of the ISSN '15 Research Review deal with the effects of ketogenic diets on the skeletal muscle anabolic response to resistance exercise, as well as its effects on weight gain in an ad-libitum diet scenario.

Read more about ISSN and other studies at the SuppVersity

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Pump Supps & Synephrine & X | ISSN'15 #2

High Protein, Body Comp & X | ISSN'15 #3

Keto Diet Re- search Update | ISSN'15 #4

The Misquantified Self & More | ISSN'15 #5

BCAA, Cholos-trum, Probiotics & Co | ISSN'15 #6

• You can build muscle on a ketogenic diet - theoretically -- While previous studies on low carbohydrate diets have already demonstrated that eating tons of fat and almost no carbohydrates can trigger improvements in body composition, it is still not clear whether the consumption of virtually carbohydrate-free diets may impair the resistance training induced anabolic response in skeletal muscle. In a previous ISSN article, for example, Paoli et al. )2012) state that their observations in gymnasts on ketogenic diets confirms that

  "the mechanism underlying the increase of body fat utilization [on ketogenic diets] has some pathways in common with mechanisms contributing to the lack of muscle mass increase [which is why] during the ketogenic diet it is actually very difficult to increase muscle mass" (Paoli. 2012).

In their latest study, researchers from the University of Tampa tried to get to the bottom of this myth by looking at the degree of muscle protein synthesis (MPS) in rodents on carbohydrate-rich Western and low-carbohydrate "ketogenic" diets (see Figure 1 for the exact macronutrient ratios).




Figure 1: Macro composition of the non-isocaloric chow (KD - 5.2 kcal/g, W - 4.5kcal/g | Mobley. 2015).

In week seven and thus after six weeks on the respective diets, the right-leg plantarflexor muscles of the researchers' "subjects", male Sprague-Dawley, were acutely exercised under isoflurane anesthesia by the means of high-frequency electrical stimulations (4 sets of 8 repetitions with 2 min recovery between sets). 90, 180 and 270 minutes after this highly controlled exercise stimulus a group of 8 rodents, each, was sacrificed and the levels of a previously injected tracer (intraperitoneal puromycin) were used as a marker for skeletal muscle protein synthesis (MPS).




Figure 2: While the absolute figures have not yet been published, I can already tell you that - statistically speaking - the type of diet did not make a difference (Mobley. 2015)

As you can see in Figure 2, the scientists observed a "main time effect for MPS". In non-scientist English this means that the training resulted in statistically significantly increase in muscle protein synthesis in the trained vs. untrained legs at 90, 180 and 270 min. What is much more important, though, is that this effect was not significantly different for the ketogenic vs. Western diet group. In conjunction with the lack of difference in phosphorylated (p)-4E-BP1 (Thr37/46) and p-rps6 (Ser235/236), two important signalling proteins that are involved in the control of skeletal muscle protein synthesis, it is thus probably warranted to conclude that "these data demonstrate that rats fed a ketogenic diet present a similar anabolic response to resistance exercise compared to rats fed a Western diet" (Mobley. 2015). Whether that's a "fair", let alone practically relevant comparison (the Western diet was lower in protein and isn't exactly a good representation of the average diet true muscle heads will be consuming) is anyone's guess, though.

While some people make it appear as if we already knew that ketogenic diets are superior, you may remember that some recent studies show that balanced diets have more favorable effects on the body composition of certain athletes | learn more

Ketogenic diets and fat free mass - an issue that requires further research in general: Only recently Grant M. Tinsley and Darryn S. Willoughby from the Baylor University highlighted in a review that a "potential loss of fat-free mass (e.g. skeletal muscle)", is a "potential concern of these “ketogenic” diets" of which the "majority of studies" suggests that it was inevitable. Since the most of these studies involve "aggressive weight loss diets" and lack an exercise component, "further research is needed to determine whether resistance training can effectively slow or stop the loss of fat-free mass typically seen in individuals following a ketogenic diet" (Tinsley. 2015). The study at hand can thus be considered the first in a line of studies on the effects and "mechanisms underlying the effects of a ketogenic diet on fat-free mass" (ibid.).

• Even if it wasn't for the questionable control diet, there would still be one thing the data from Mobley's study cannot tell us and that's whether the putative reduction in IGF-1 that has been observed on low carbohydrate diets (Caton. 2012) may have long(er)-term detrimental effects on muscle gains. There is, as you as a SuppVersity reader will know, good evidence that IGF-1, despite its irrelevance for short term increases in muscle protein synthesis, may play an important role in the long-term adaptational response to exercise (I suggest you go back to this SuppVersity Classic Article if that's news to you). It's thus not just the fact that we are dealing with a rodent study here that makes me want to say that future long(er) term studies in humans are necessary before the myth that ketogenic diets may impair (long-term) gains can be put to rest once and for all.
• Is weight gain hardly possible on the ketogenic diet? Actually this is another common ketogenic diet myth: When you are consuming a ketogenic diet you cannot get fat. Sounds stupid, right? Well, if you look at a recent study that comes - just as the previously cited study - from the University of Tampa (Holland. 2015), would certainly appear as if there may be something to this claim.
  
  In their 6-week rodent study, Angelina M. Holland and colleagues compared the effects of ketogenic (KD), Western (WD), and standard chow (StdChow) control diets on fat deposition and serum health-related biomarkers (exact macronutrient ratios are given in Figure 3).
  

  

  Figure 3: Macronutrient composition of the diets in Holland's study (Holland. 2015).

  Over the course of the study, the scientists' "subjects", male Sprague-Dawley rats (~9-10 weeks of age) were provided isocaloric amounts of either a KD (5.2 kcal/g, 20.2% protein, 10.3% carbohydrate, 69.5% fat; n = 50), WD (4.5 kcal/g, 15.2% protein, 42.7% carbohydrate, 42.0% fat; n = 66), or StdChow (3.1 kcal/g, 24.0% protein, 58.0% carbohydrate, 18.0% fat n = 10). At the end of the study the exact daily food intake and body weights were recorded and the animals were sacrificed in order to analyze the weight of four different fat depots.
  
  As it was to be expected, the rats on the ketogenic diet consumed slightly less energy (3,540 ± 74 kcal) than those on the western diet (3,638 ± 83 kcal) over the course of the six week study. It is thus not surprising that there was a significant inter-group difference in terms in terms of the total amount of weight rodents in the KD and WD group gained: 397g vs. 494g to be precise.
  

  

  Figure 4: Due to a significantly reduced feed efficacy (weight gain per energy intake) the rats on the ketogenic diet gained sign. less weight than both, the rats on the Western diet and standard chow (Holland. 2015).

  What may come as a surprise, though, is the generally reduced feed efficiency (=amount of body weight gained per kcal the rodents consumed) of the ketogenic diet. With a feed efficacy of only 0.018g/kcal, the ketogenic diet was significantly less fattening than the Western diet (0.042 ± 0.007g/kcal) and the standard chow (0.045 ± 0.012g/kcal).
  
  That's a quite a remarkable result, but if the lack of weight gain applied only to the total amount of body weight, it would be difficult to decide whether that's a good or a bad thing. When the scientists took a look at the weight of the fat depots, however, it became clear that the lion's share of the weight difference was mediated by a lack of fat, not just weight gain.

  "KD and StdChow had significantly less absolute and relative omental (absolute omental: 0.8 ± 0.3g and 1.2 ± 0.4g vs 1.6 ± 0.6g, respectively, p < 0.05; relative omental: 2.1 ± 0.7 and 2.4 ± 0.7 vs 3.2 ± 1.2g/kg, respectively, p < 0.05) compared to WD rats. KD and StdChow also had significantly less perirenal adipose tissue compared to WD (absolute perirenal: 4.2 ± 1.3 and 5.4 ± 1.4 vs 7.8 ± 1.8g, respectively, p < 0.05; relative perirenal: 10.6 ± 2.8 and 11.4 ± 2.4 vs 15.6 ± 3.0g/kg, respectively, p < 0.05). KD had significantly less absolute inguinal subcutaneous (SQ) and scapular brown fat than WD (absolute SQ: 4.3 ± 1.5 vs 6.6 ± 2.4g/kg; absolute brown fat: 0.6 ± 0.2 vs 0.8 ± 0.3g) but similar relative SQ and brown fat weights" (Holland. 2015).

  In view of the concomitantly reduced serum triglyceride levels (WD - 319.7 ± 109.8mg/dL versus StdChow 163.0 ± 67.0mg/dL and KD 69.9 ± 21.2mg/dL; p < 0.05), serum cholesterol and glucose levels glucose, the claim that ketogenic diets may help mammals to maintain stable body weights while improving, not messing with their glucose and lipid metabolism does therefore appear to be clearly supported by the study at hand. All that still has to be done before we can remove the "?" from the subheading that precedes the previous paragraphs would be a human study with a similar / identical design to exclude that any differences in glucose and, more importantly, fat metabolism in human beings increase the feed efficacy of the ketogenic diet to an extent that nullifies the benefits.

Are you looking for an unconventional nootropic? Look no further. Morning cardio on empty could be just what you've been looking for. Learn more in "Breaking the Fast, Cardio & Your Brain: Cardio on Empty is Fatiguing. Fasting Without Exercise, However, Can Have Nootropic Effects"

Which studies didn't make it into this installment of the ISSN '15 Research Review? This time, three studies didn't make the cut. There's Jason Cholewa's study on the "effects of a sports nutrition education intervention on nutritional status, sport nutrition knowledge, body composition, and performance in NCAA Division I baseball players," which may make it into a special on the importance of sport nutrition knowledge, when the full text is published, Solomon et al.'s study on the "efficacy study of alpha BRAIN®" as a nootropic where I would like to see the absolute improvements and the respective standard deviations in cognitive performance before discussing the study in the SuppVersity news, as well as Jones' and Davidson's investigations into the "proportionality of skeletal muscle before and after intervention" the significance of which would go unappreciated if I simply summarized the little information from the abstract | Comment on Facebook!

References

• Caton, Samantha J., et al. "Low-carbohydrate high-fat diets in combination with daily exercise in rats: effects on body weight regulation, body composition and exercise capacity." Physiology & behavior 106.2 (2012): 185-192.
• Cholewa, Jason M., et al. "The effects of a sports nutrition education intervention on nutritional status, sport nutrition knowledge, body composition, and performance in NCAA Division I baseball players." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P44.
• Holland, Angelia M., et al. "Ketogenic versus Western and standard chow diets favorably alters fat deposition and serum biomarkers in rats." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P21.
• Jones, Brian A., and Robert T. Davidson. "Muscle proportionality: The proportionality of skeletal muscle before and after intervention." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P51.
• Mobley, C. Brooks, et al. "The anabolic skeletal muscle response to acute resistance exercise is not impaired in rats fed a ketogenic diet." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P22.
• Paoli, Antonio, et al. "Ketogenic diet does not affect strength performance in elite artistic gymnasts." Journal of the International Society of Sports Nutrition 9.1 (2012): 34.
• Solomon, Todd M., et al. "A randomized, double-blind, placebo controlled, parallel group, efficacy study of alpha BRAIN® administered orally." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P54.

High Fat, Low Protein to Induce Ketosis

Truly ketogenic diets have recently lost much of the attention they received at the beginning of the 21st century. And today, many people refer to every low carb diet as "keto" or being "ketogenic". Research from scientists from Germany, however, have now found that ...

the absence of dietary carbohydrates per se does not induce ketosis. LC-HFDs [low carb high fat diets] must be high in fat, but also low in protein contents to be clearly ketogenic. Independent of the macronutrient composition, LC-HFD-induced weight loss is not due to increased EE and LA.

So probably few of those hardcore keto-dieters out there will eventually end up in "true" ketosis. A positive thing, if you asked me, because although I am a low carb guy, I am not a no carb guy ;-)

Greater Dietary Fat Oxidation in Obese Men: Finally an Advantage of Being Fat

Some good news for all fat, yet healthy students of the SuppVersity. Scientists at the University of Oxford cooperated with some colleagues from the University of Ottawa Heart Institute (Hodson. 12 July 2010) and found that

The contribution of fatty acids from splanchnic sources was higher (P<0.05) in the abdominally-obese group. Ketogenesis occurred to a significantly greater extent in abdominally-obese compared to lean males largely due to lessened down-regulation of postprandial ketogenesis (P<0.001).

Not only does this tell us, that our bodies try to protect themselves from fat-deposition in the liver and other organs. It might also shed additional light onto the effectiveness of low-carb diets in obese individuals.